How many combinations...

W

Waffle

Alpha Geek
Had a discussion today concerning the total number of possible 4 digit combinations using the numbers 0 - 9, as seen on pin codes etc.

I've worked it out to be 10,000 possible combinations, but what I can't understand is how practically every person (in the uk at least) has a unique 4 digit pin code? Surely 10,000 is too little to deal with a whole county!

Anyone clarify this?
 
That’s true, buts it’s very easy to remember, for the customer. There are other security measures that banks take, other than 4 digits. E.g. if you enter the wrong number the machine will swallow your card.
 
The thing is that the PIN is tied to an account. In otherwords, each account has 10,000 possibilities for it's PIN.
 
Not everyone has a different pin.

An account number is like 8 digits, a card number is 16.

So there's 10^8 account numbers and 10^16 different card numbers. Each account has 10^4 possible pin-numbers.

So it's the account / card number that's unique for each person, not the pin number.
 
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